Annular hole cutting tools typically have an arbor connected to an annular, hollow cutter for cutting a hole in a workpiece. A pointed ejector member, or pilot drill, is mounted in the cutter. As the rotating arbor is advanced toward the workpiece, the drill drills a pilot hole into the workpiece to center the annular cutter.
A similar device is illustrated in U.S Pat. No. 4,408,935 issued Oct. 11, 1983 to Masaaki Miyanaga for xe2x80x9cMetal Borerxe2x80x9d. A set screw on the spindle engages a groove in the ejector to prevent it from being totally ejected from the spindle. If the set screw is removed from the groove, a spring will tend to totally eject the pointed ejector member from the arbor, creating a dangerous situation.
The broad purpose of the present invention is to provide an arbor assembly for supporting both a hole cutter and a spring-biased drill pilot. A set screw connects the arbor to the hole cutter so that they rotate as a unit. A second set screw on the arbor engages a longitudinal flat surface on the drill pilot to permit it to move axially with respect to the hole cutter, while rotating with the arbor. The inner end of the drill pilot has a collar that is larger than the diameter of the center bore of the hole cutter so that the drill pilot cannot pass through the hole cutter in the event the second set screw is disengaged from the flat on the drill pilot.
Still further objects and advantages of the invention will become readily apparent to those skilled in the art to which the invention pertains upon reference to the following detailed description.